The drug abuse problem in general and the widespread use of marijuana in particular have focused attention on the chemistry and pharmacology of the plant Cannabis sativa. In the decade since the discovery of the cannabinoid receptors, much progress has been made in the cannabinoid field. It has been established that there are at least two types of cannabinoid receptors: CB1 receptors which are present both inside and outside the central nervous system (CMS) and CB2 receptors which are found mainly in the periphery. Two main endogenous ligands have been discovered, anandamide (AEA) and 2-arachidonyl-glycerol (2-Ara-GI). Also known as endocannabinoids, they are both present in central as well as peripheral tissues. Several chemically distinct and diverse structural classes of compounds which have no chemical/ structural relationships have been discovered as ligands for the cannabinoid receptors. The goal of the proposed synthetic research is to generate chemical probes which will help in understanding the mechanisms involved and the role of endocannabinoids in the CMS and the periphery. Our Specific Aims are (1) development of allosteric modulators of the cannabinoids CB1 receptors, (2) development of DAGL-a inhibitors, (3) development of selective inhibitors of enzymes involved in endocannabinoid metabolism and (4) supply AEA, 2-Ara-GI and ligands of interest to investigators for the other projects for further biological testing. The synthesis of the analogs will provide endocannabinoid probes for the in vitro and in vivo studies and the results could point us in the direction of other cannabinoid receptor subtypes, reveal mechanisms involved in brain function and lead to therapeutic drugs in the areas of inflammation, pain, immune response, neuroprotection in head injury and other CMS related diseases. The proposed study will help our understanding of the pharmacological action of this important class of compounds and provide drugs in the health care field.